A Fashionable Flat

English elegance meets Italian brio in a fashion innovator's London home

The most fashionable clothing isn't flattering if you don't feel comfortable and confident in it. Ditto a gorgeous house: It isn't a home unless you can kick off your shoes and relax—or play. In London, Sofia and Niccolo Barattieri di San Pietro have created a haven that lets them do just that.

"It's the Italian way," says Paolo Moschino, the designer who recently renovated the couple's apartment. "In Italy, you might have a big palazzo, but you serve mozzarella and tomatoes for lunch, and your guests are all laughing and talking. It's a relaxed approach within the historical grandeur of a room."

This attitude makes intuitive sense to the Barattieris. Both Sofia and Niccolo were born and raised in Italy, though the couple never met back home. "We arrived in London the same week," says Sofia, "and we each called the one person we knew. That's how we were introduced. It was completely unexpected." Yet the union made perfect sense. Husband and wife had both spent childhood summers by the Mediterranean—she on the Amalfi coast, he on the Tuscan—and they shared a love for the sea, as well as a passion for the cosmopolitan buzz of the city.

In other ways, too, Sofia's past has serendipitously reemerged to shape her London life. Three years ago, her lifelong love of fashion inspired an innovative business venture. She and her best friend (and favorite shopping partner in crime) noticed that most e-commerce transactions happened in isolation, despite the fact that real-life shopping is always more fun when done à deux. So they set out to create a high-end fashion website, Motilo, that would combine the best aspects of social media with the pleasures of boutique hopping. Pop-up windows allow users to communicate with friends about selections, and "Motilo girls" offer ideas on how to combine pieces to create different outfits. "Everybody needs a second opinion," says Sofia. "Humans are gregarious beings. And fashion is communication—something you do with a laugh. That's why we started Motilo."

To conjure a similar feeling of playfulness in their home, the Barattieris sought out Moschino. Sofia initially tracked him down after admiring the work he'd done on a friend's interiors. But for Moschino, a mere referral does not a client make. A protégé of the celebrated British decorator Nicky Haslam, Moschino now owns the Haslam firm, so he's choosy about taking on design projects. "When I meet someone, the most important thing is to have a connection," he says. "Most of my clients become best friends."

As Sofia puts it, "With Paolo, it was love at first sight. He's Italian, and he has exquisite taste."

Yet taste alone was not going to suffice for this project. Some serious engineering was required too. The Barattieris were living in a duplex flat in Kensington, and, with two kids, they were starting to run out of space. After their family had grown again—they now have three children, ages nine, six, and two—the apartment next door fortuitously went on the market, allowing them to triple their square footage. "I went for it," says Sofia. "I was very lucky."

Less fortunate, perhaps, was the architecture firm, Tyler Mandic, which had to figure out how to seamlessly join the flats, which were on two floors of adjacent townhouses separated by a load-bearing wall. "It was very complicated—and scary," says Gordana Mandic. Engineers had to transfer the weight of the five-story buildings onto columns and beams without the slightest shift, which might have created cracks in the half dozen well-appointed flats upstairs.

It went off without a hitch, and the palatial space opened up like a starfish. "My priority is always to make it beautiful and make it flow," says Moschino. To that end, he wove echoes of the Mediterranean throughout. The color palette includes splashes of aquamarine, turquoise, and emerald in nearly every room. Mercury-glass panels create an oystershell shimmer in the entry hall and around the fireplace. For sparkle, he used lots of glass: vintage glass-column floor lamps in the entry, Murano-glass bowls in the drawing room, and numerous vases and objets throughout. Jute carpets underfoot provide a soft counterpoint to the sumptuous, ebonized-oak floors.

Italy is evoked in other ways as well. The curved ceiling of the main staircase was inspired by the courtyard stairways of Tuscany. Expanses of marble line the kitchen and bathrooms. A series of French doors opens onto a private terrace and vast communal garden beyond, and allows for an indoor-outdoor lifestyle. "The children have great friends in the garden," says Sofia. "I can just tell them to go—they run from one house to another."

The kitchen was the previous owner's living room. "It's a dream," says Sofia, who loves to cook and is often surrounded by friends for dinners that run past midnight. Catwalk-style lights, a nod to her work, are rigged overhead. But the scene they illuminate is a far cry from the runways of Paris or Milan. "Houses are completely different from fashion," says Moschino. "You have to think of a house as forever, even if it's not. You can't design for the flash of a moment."